MAKE IT SIMPLE NETWORKING: March 2020

Saturday, 21 March 2020

Friday, 20 March 2020

MAC ADDRESS

MAC ADDRESS: MEDIA ACCESS CONTROLLER

It is a 48 bit hexadecimal value, assigned to a network interface controller (NIC) /

network card / Ethernet card / Wi-Fi card.

It is a physical address in communications within a network segment .

First 24 bits OUI (Organizationally Unique Identifier)/ Last 24 bits NIC-specific

Least Significant bit of the most significant byte

8th bit (LSB)	I/G (Individual/Group) → 0 = Unicast (one-to-one), 1 = Multicast/Broadcast
7th bit	U/L (Universal/Local) → 0 = Globally unique (from manufacturer), 1 = Locally administered (manually changed / overridden)

How to Find MAC address:

In phone - settings - About phone - detailed info/specs – status

In system - press Windows key + R, In command prompt - Run cmd = ipconfig/all

MAC Address, IP Address Range, Port numbers and Protocol numbers

MAC Address ( Media Access Control Address ) : Physical Address

Unique identifier assigned to a network interface controller (NIC) / network card / Ethernet card / Wi-Fi card is use as a network address in communications within a network segment .

Hexadecimal - 12 digit and Binary - 6-Byte -48 Bits

30-65-EC-6F-C4-58

NIC - Network Interface Controller Specific / UAA - Universally Administered Address

IG (Individual Group) bit is the least significant bit in this byte / LG (Local/Global) bit is the second least significant bit in this byte.

IP Address Range:

Public IP - WAN

CLASS A 0.0.0.0 - 127.255.255.255 /8
CLASS B 128.0.0.0 - 191.255.255.255 /16
CLASS C 192.0.0.0 - 223.255.255.255 /24
CLASS D 224.0.0.0 - 239.255.255.255 /32
CLASS E 240.0.0.0 - 255.255.255.255 /64

Private IP - LAN

CLASS A 192.168.0.0 – 192.168.255.255 /8 (65,536 IP addresses)
CLASS B 172.16.0.0 – 172.31.255.255 /12 (1,048,576 IP addresses)
CLASS C 10.0.0.0 – 10.255.255.255 /16 (16,777,216 IP addresses)

APIPA - CLASS B 169.254.0.1–169.254.255.254 /16
(Auto Private IP Address)

Loopback - CLASS A 127.0. 0.1 – 127.255. 255.255 /8
(For checking the PC working properly)

Static IP - bought to maintain the same IP-Address always.

Unicast: L1 Source IP --> Destination IP
L2 Source PC MAC --> Destination MAC
Multicast: L1 Source PC IP --> 224.0. 0.0 to 239.255. 255.255
L2 Source PC MAC --> Destination MAC
Broadcast: L1 Source PC IP --> Destination IP 255.255.255.255
L2 Source PC MAC --> Destination MAC FF.FF.FF.FF.FF.FF

PROTOCOL	EXPANSION
ARP	Address Resolution Protocol
RARP	Reverse Address Resolution Protocol
GRAP	Gratuitous Address Resolution Protocol
ADSL	Asymmetric digital subscriber line
STP	Spanning Tree Protocol
LDAP	Lightweight Directory Access Protocol
LLDP	Link Layer Discovery Protocol
VTP	VLAN Trunking Protocol
PPP	Point-to-Point Protocol
IS-IS	Intermediate System to Intermediate System

PROTOCOL	EXPANSION	PORT NUMBER	TRNX TYPE
DNS	Domain Name System	53	TCP/UDP
DHCP	Dynamic Host Configuration Protocol	67,68	UDP
NTP	Network Time Protocol	123	UDP
TFTP	Trivial File Transfer Protocol	69	UDP
RIP	Routing Information Protocol	520	UDP
ISAKMP	Internet Security Association and
	Key Management Protocol	500	UDP
SYSLOG	System Logging Protocol	514	UDP
SMTP	Simple Mail Transfer Protocol	25	TCP
FTP	File transfer protocol	20/21	TCP
BGP	Border Gateway Protocol	179	TCP
HTTP	Hypertext Transfer Protocol	80	TCP
HTTPS	Hypertext Transfer Protocol Secure	443	TCP
KERBEROS	Cerberus	88	TCP
POP3	Post Office Protocol version 3	110	TCP
NFS	Network File System	111	TCP/UDP
IMAP	Internet Message Access Protocol	143	TCP/UDP
SNMP	Simple Network Management Protocol	161	TCP/UDP
SNMP-TRAP	traps for monitoring	162	TCP/UDP
SSH	Secure Shell	22	TCP
Telnet	TELecommunication NETwork	23	TCP
SFTP	SSH File Transfer Protocol	22	TCP

PROTOCOL	EXPANSION	PROTOCOL NUMBER
TCP	Transmission Control Protocol	6
UDP	User Datagram Protocol	17
ICMP	Internet Control Message Protocol	1
IGMP	Internet Group Management Protocol	2
GRE	Generic Routing Encapsulation	47
ESP	Encapsulating Security Payload	50
AH	Authentication Header	51
OSPF	Open Shortest Path First	89
EIGRP	Enhanced Interior Gateway Routing Protocol	88
VRRP	Virtual Router Redundancy Protocol	112

OSI Layer Model and TCP/IP Model

OSI Layer (Reference Model): Open Systems Interconnection
(developed by ISO – ‘International Organization of Standardization in 1984)

Interoperable communication between different vendors

1. Physical Layer : Binary Transmission

It is the first of the osi model
It establishes a physical connection between the devices using wires and cables.
Eg : twisted pair and coaxial cable and optical fiber cable(SONET)
In which datas are transferred in the form of bits (0s,1s)
Functions :

Bit synchronization: data circuit-terminating equipment (DCE), data terminal equipment (DTE) using Clock signal.
Bit rate control: transmission rate i.e. the number of bits sent per second
Physical topologies: network structure i.e. bus,star or mesh topology
Transmission mode (Data flow): Simplex,half-duplex and full-duplex.

Devices : Hub,repeater,Modem,Ethernet Cables,PCs,etc
Protocol : ADSL Asymmetric digital subscriber line, ISDN Integrated Services Digital Network, SDH Synchronous Digital Hierarchy, SONET Synchronous Optical Networking.

2. Data-Link Layer : Physical Addressing

The data link layer is responsible for the node to node error-free delivery over the physical layer.
Datas are transferred in the form of frames.
Functions :

Flow control, Error control and Access control
Data Link Layer is divided into two sub layers :

i. Logical Link Control (LLC) - CRC checks and control error and frame synchronization
ii. Media Access Control (MAC) - Physical Addressing and data encapsulation.

Devices: Switches
Protocols: ARP, RARP, GARP, PPP, STP, LLDP, VTP

3. Network Layer : Logical Addressing

Logical Addressing using IPV4 and IPV6
Network layer converts the received segment into packets.
Functions:

1.Path determination through ip routing
2.Handles network traffic i.e network conjunction.
3.Adds source address, destination address and sequence number to each packet.

Devices: Routers and L3 Switches
Protocols: IP, ICMP, IGMP, IPsec.

4. Transport Layer: End-To-End connection reliability

It is the Heart of OSI layer
Data is transferred in the form of segments.
Functions:

Establishes End to End Delivery of data
Reliability
Error control and Flow control
Segmentation
MUX

Devices: Firewall
Protocols: TCP and UDP

5. Session Layer: Inter-host Communication

Functions:

It has APIs (Application Programming Interfaces). Eg:- NetBIOS(Net Basic Input Output Systems)
Session Management: For generating session ID, establishment, maintenance and termination the sessions between the client and the server
Synchronization : checkpoints are added to identify the errors
Dialog Controller : communication - simplex, half-duplex or full-duplex.
Token management i.e preventing two parties from attempting the same critical operation simultaneously
Authentication, Authorization and Accounting.

Devices: Gateways, Firewalls, PC's
Protocols: PPTP, SCP, SDP, SMPP, RPC, API

6. Presentation Layer: Data representation and encryption

Functions:

Translation : ASCII to EBCDIC.
Encryption/ Decryption : Data encryption translates the encrypted data(cipher text) into decrypted data (plain text) vice-versa using a key value.
Compression/Decompression : Reduces the number of bits that need to be transmitted on the network vice-versa.

Protocols: NCP,AFP,LLP,SSL(encryption)

7. Application Layer: Network process to Application

Layer interacting directly with the user.
Functions:

Network Virtual Terminal
FTAM-File transfer access and management
Mail Services SMTP
Directory Services

Protocols: HTTP,DNS,FTP,DHCP

Thursday, 19 March 2020

IPV 4 and IP Header format

IPV4 (Internet protocol Version 4)

32 bit dotted decimal value
Splitted into 4 octets
Each contains 8 bits
Overall 4.3 billion address are available.
There are two different areas .

Network => Network represent area
Host => Host represent the users in the area

1st Octet plays the major role of dividing classes

128 + 64 + 32 +16 + 8 + 4 + 2 + 1 = 255.

There are 5 classes:

Class A: 1st Octet 8th bit always 0

A 8 bit Network and 24 bit Host ( 1 octet network 1x8 = 8 and 3 octet host = 8x3 = 24)

Starts at 0.0.0.0 - 127.255.255.255

0.0.0.0– Not for communication

127.0.0.0 – Loopback Address used by system

User Access Address 1.0.0.0 - 126.255.255.255

Subnet mask - To differentiate host bits and network bits

Host bits are represented as 0 and Network bits are represented as 1

How many users can access Class A network

2^h - 2 = value (h = number of host bits)

2^24 - 2 = 1,67,77,214 Users can access

PING Google - Packet flow

ARP Header and ARP Types

ARP (Address Resolution Protocol)

L2 layer protocol, it is encapsulated in Ethernet-II frame
It use to resolve the L2 mac address using L3 ip address
Arp cache maintains a correlation between MAC and IP address.

Types of ARP:

>> RARP

>> GARP
>> Proxy ARP

RARP - Reverse ARP

Before DHCP, RARP is used. RARP provides only the IP Address, but DHCP provides ip address along with 255 parameters.

GARP - Gratuitous ARP

It is used to avoid IP Address conflict, where the source and target ip will be same
The PC will broadcast an ARP request, and checks whether the received ip address is already in use by some other PC in the network.
It is used in high availability protocols like VRRP (Virtual Router Redundancy Protocol)

Proxy ARP - Duplicate Gateway.

When the source and the destination are in the same network but different subnet, then the default gateway will provide its own MAC Address on behalf of the destination.

Ethernet II frame : IEEE 802.3

TCP VS UDP

TCP (Transmission Control Protocol)	UDP (User Datagram Protocol)
It is a heavy weight protocol	It is a light weight protocol
Connection-oriented (uses a 3-way handshake to establish connection, 4-way handshake to close as acknowledgement	Connectionless (no handshake)
Ensures reliable delivery of data(checks error and retransmits the lost packets)	Unreliable delivery (no retransmission)
Uses fixed windowing and sliding windowing for congestion and flow control	No flow control or congestion control
Slower due to reliability mechanisms	Fast data transmission
Segments data and ensures ordered delivery	Sends datas independently without any order.
Web browsing (HTTP/HTTPS), File transfer (FTP), Email (SMTP, IMAP, POP3)	Online gaming, Video streaming, VoIP, DNS queries

TCP

TCP (Transmission Control Protocol): protocol number- 6

Transport layer protocol - connection-oriented protocol
Responsible for reliable delivery of data
transmission time is relatively less
Uses 3 way Handshake for establishing connection and 4 way handshake for closing
uses Windowing - sliding window and zero window
protocols such as HTTP, HTTPs, FTP, SMTP, Telnet uses TCP

TCP Features:

Stream based flow: it ensure stream delivery of data
MULTIPLEXING/DEMULTIPLEXING: Able to run multiple applications with single ip using different port numbers.
ERROR DETECTION: using checksum
LOSS DETECTION: The segment get lost and never reached the destination
ERROR/LOSS RECOVERY: To overcome error and loss detection . Re-transmission takes place based on the buffer size.
FLOW CONTROL: To ensure whether both the sender and receiver have enough buffers to accommodate the data.
CONGESTION CONTROL: Ensuring the network has capacity of transferring the data through the underlying layers without any trafic.
RELIABILITY: TCP negotiates certain parameters to make it reliable, same bit order in the destination without any packet.

TCP windowing :

Used to avoid congestion in the traffic.
It controls the amount of unacknowledged data a sender can send before it gets an acknowledgement back from the receiver that it has received it.
It is one of the key factors for efficient data transmission.
It can also be known as a form of flow control where the host indicates the sender how much data can be accepted and wait for the further instructions.

MAKE IT SIMPLE NETWORKING

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Saturday, 21 March 2020